Various orthopedic surgical procedures require the locking or securing together of adjacent bones or broken bones. In the field of foot and ankle surgery, indications for reconstruction including osteotomy or arthrodesis are well documented in the medical literature as the standard to alleviate pain and infection, minimize limb loss, and maximize physical capacity to return to all activities of daily living or sports.
Technically, the above-mentioned types of surgery are complicated by the reality of weight bearing of the extremity. The most salient issue involved with healing of foot osteotomies is the complex loadbearing which is seen in the foot uniquely. Specifically, body weight axes of force vector down whereas a supporting surface, i.e. the floor, pushes back up. A bending moment is created along the medial and lateral columns of the foot.
The medial column comprises the first metatarsal, medial cuneiform, navicular, and talus bones. The lateral column comprises the fifth metatarsal, fourth metatarsal, cuboid, and calcaneus bones. The joint surfaces of the aforementioned bones that articulate are, for the most part, flat. These bones are stabilized, therefore, by dense and extraordinarily strong ligaments in every possible anatomic arrangement; some linear, some oblique, some crisscross. Unless injured by trauma or metabolic diseases such as advanced diabetes, these ligaments provide excellent stability for a lifetime of gait. However, when they lose their function, the articular surfaces are destroyed rather quickly by the unremitting forces of tension on the plantar surfaces and compression on the dorsal surfaces of the ligaments and their attendant bones.
In the field of podiatry and orthopedics a variety of solutions to facilitate arthrodesis and fusion across the joint surfaces has been promoted over the years. Initial approaches used simple K wires, followed by internal wire fixation with the K wires. This provided a combination of cerclage and K wire; one for compression, the other for alignment. Subsequent to this we adopted the principles of rigid fixation with micromotion, minimization, and strict non-weightbearing for 6 weeks or longer were utilized to facilitate primary bone healing without callus. Unfortunately, this method has its limitations as well since most patients are unable to stay off their feet for 6 weeks. Diabetics with neuropathy are even more unaware of how they are standing on their foot. Noncompliance with the requirement to stay off the foot typically results in failure of the procedure.
Another approach was to revert to external fixation with an Ilizarov fixator to engender bound wire fixation in combination with internal fixation. This synergistic combination provided higher compression than either form on an isolated basis. In fact limited weight bearing can be encouraged during the perioperative period. External fixation has its limitations as well. Most surgeons do not want to use external fixation because of its technical difficulty, its foreboding appearance, and the requisite constant follow-up during the perioperative period in the doctor's office, which may be financially unreasonable for some practitioners.
Many of the currently trained surgeons in the U.S. practicing foot and ankle surgery refer the use of locking plate technology. This new technology has been alleged to simulate the rigidity engendered by an external fixator. Nevertheless locking plates have not been suggested to be tenable for immediate weight bearing even on a limited basis after for reconstruction. Some more advanced practitioners use a combination of screw fixation with a plate placed over it, but the possibility of motion at the arthrodesis site remains.
For example, one common procedure in foot surgeries is directed to securing together the adjacent first metatarsal and medial cuneiform bones. Using known procedures and surgical devices, a patient can be immobilized for extended periods. Common procedures used in these foot surgeries include the use of a plate fixation lapidus as illustrated in FIG. 3. As is evident in FIG. 3, a locking plate 510 is fixed into the top or dorsal side of the adjacent first metatarsal 2 and medial cuneiform 3 bones. That plate is screwed into the tops of those bones 2,3 with the locking screws 512 shown.
Alternatively, a crossing screw fixation for lapidus procedure may be used, as illustrated in FIG. 4. In this procedure, locking screws 522 are installed through the adjacent first metatarsal 2 and medical cuneiform 3 bones, respectively, and across the first metatarsal-cuneiform joint 4 in a crisscrossing pattern as shown in FIG. 4. The bones 2 and 3 as a result, are fixed together in an effort to protect against the compression and tension directions of force when the foot is stood upon. The compression 5 and tension 6 forces that are experienced by the foot when bearing load of the body are illustrated in FIG. 3.
Both the plate fixation lapidus and crossing screw fixation for lapidus procedures (shown in FIGS. 3 and 4, respectively) have limitations in view of the substantial stresses that are applied to those foot bones during normal ambulation by a patient. Accordingly, in each example, there is limited effectiveness for these repair types of surgery.
Grady, Jr. et al. in U.S. Pat. No. 7,951,176 discloses a bone plate for use in reducing a bone fracture of the femur. Bone anchors (screws) are passed through the bone plate and into the bone of the femur to secure the plate to the femur. The shafts of the bone screws may touch or nearly touch at the point of intersection, such that the first and second bone anchors form a truss. While this “truss” formation may provide additional support to the compression forces experienced in the femur, this construction does nothing to provide further support for tension forces such as those experienced in the foot under load bearing.
There is a continuing need for solutions for the ultimate stabilization of the arthrodesis site of the weight bearing column of the foot. The present invention provides such solutions as well as solutions for improving the stabilization provided by surgical procedures to secure broken bone portions or adjacent bones in other orthopedic fields.